The field of the invention generally pertains to air blower assemblies. The invention relates more particularly to air blower assemblies used with spas having vibration-dampening elastomeric gaskets for mounting the blower-and-motor units, and a muffler member for reducing air intake noise.
Air blower assemblies have commonly been used with spas to force compressed air through numerous small apertures in the wall of a spa tub, below the water level, thereby creating a bubbling effect in the water. This creates a relaxing environment which enhances the bathing experience.
Perhaps the greatest disadvantage of air blower assemblies, however, is the noise associated with the blower-and-motor units used to pump the compressed air into the water-filled spa tubs. The noise is primarily attributable to the high speeds and noise-producing vibration generated by the blower-and-motor units. Additionally, air rushing directly into the air blower assembly during air induction creates a typically high-pitched whine. Both sources of noise can disturb and detract away from the relaxing atmosphere of the spa.
Various methods have been developed to reduce the noise created by air blower assemblies used with spas. One method has been to line the internal surface of the structure enclosing the blower-and-motor unit with sound-insulating material. In U.S. Pat. No. 4,950,133 an air blower assembly is shown having an inverted cup-shaped cover fitted over the open side of a cup-shaped base to define an enclosed air chamber above a blower-and-motor unit mounted in the cup-shaped base. An elongated air passage defined by the cup-shaped base leads air into the enclosed air chamber from an air inlet port. Both the enclosed air chamber and the elongated air passage are lined extensively with acoustical foam.
This method, however, can make the air blower assembly excessively bulky, resulting from the concentric placement of the acoustical foam lining in relation to the elongated air passage used for air induction. As can be best seen in FIG. 4 and FIG. 6 of U.S. Pat. No. 4,950,133, this arrangement increases the diameter of the air blower assembly considerably. As shown in FIG. 6, the elongated inlet passages, indicated by reference characters 50, 51, and 52, form an additional concentric layer surrounding the blocks of acoustic foam material, indicated by reference characters 67, 68, and 69.
Additionally, various methods of mounting the blower-and-motor units have been used to reduce noise-producing vibration generated by air blower assemblies. In U.S. Pat. No. 4,950,133, discussed above, the air blower assembly has a blower-and-motor unit centrally mounted on a platform portion of a cup-shaped base by means of an acoustical foam nest. The acoustical foam nest rests inside the platform portion supporting only the enlarged blower portion of the blower-and-motor unit, with the attached motor portion extending through a central opening of the platform portion. A strap secures the blower-and-motor unit to the acoustical foam nest and the cup-shaped base. Another example is shown in U.S. Pat. No. 5,068,555 disclosing a dust exhauster. The dust exhauster has a commutatorless D.C. electric motor/turbine unit which is mounted between a lower support plate and an upper anchoring plate using rubber elements.
The existing mounting methods, however, have been largely inadequate in dampening the noise-producing vibration generated by blower-and-motor units. The mounts used in the prior disclosures are molded to contour exactly to the surface of both the blower-and-motor units and the mounting surfaces, typically a housing structure. Complete surface-to-surface contact can improve transfer, not dampening, of vibration from the blower-and-motor unit to the enclosing housing structure.